The steady-state total plasma clearance of exogenous vasopressin will be measured in physiological conditions: (a) in conscious overhydrated dogs and sheep, with plasma concentrations in or very near the physiological range (i.e., at 5-10 microunits per ml); (b) in the same animals on the same day, with the plasma concentration at 500 microunits per ml, to learn if total clearance is dependent on the plasma concentration; and (c) in ethanol-anesthetized overhydrated rats, with plasma concentrations at 5-10 and at 500 microunits per ml. It is also proposed to measure simultaneously the total, renal and urinary clearances of exogenous vasopressin in conscious overhydrated dogs and sheep with the plasma concentration at 10 microunits per ml. The plasma will be extracted, and the extracts will be concentrated and then assayed in ethanol-anesthetized rats in a 2x2 design. Catheters will be placed in prior aseptic surgery.